Multimedia broadcast multicast service (MBMS) is multimedia broadcast multicast function defined in 3rd generation partnership project (3GPP) R6, it is used for providing multimedia broadcast and multicast service to users in wireless cell. In long term evolution (LTE) system, MBMS dedicated frequency layer and frequency layer shared with non-MBMS service could all provide MBMS, the LTE cell supporting MBMS could be MBMS dedicated cell, also could be MBMS/unicast mixing cell.
Therein, MBMS dedicated frequency layer is the frequency layer which is dedicated for MBMS transmission, when a cell is configured as MBMS dedicated frequency layer, that cell is MBMS dedicated cell; when a cell is configured as frequency layer which is non-dedicated for MBMS transmission, that cell is MBMS/unicast mixing cell, the MBMS/unicast mixing cell transmits MBMS and unicast service in collaboration, some time is used for MBMS service transmission, other time is used for unicast service transmission. MBMS could be transmitted in single cell, or in multiple cells. The single cell transmission of MBMS means MBMS only transmitted in coverage of a specified cell, it doesn't support combination transmission of MBMS in multiple cells. However, the multiple cells transmission of MBMS needs the support of the transmission manner of multicast broadcast single frequency network (MBSFN).
MBSFN is the manner that performs synchronous transmission in multiple cells with same frequency at same time, it could thrift frequency resources, and improve utilization rate of spectrum. MBSFN requires the multiple cells send same data at same time, receiver of user equipment (UE) could consider the multiple MBSFN cells as a single big cell. There would not be interference from neighbor cells, and the signal strength would be increased by superimposing signal from multiple MBSFN cells. MBMS dedicated cell and MBMS/unicast mixing cell could all use MBSFN transmission mode. In addition, by using advanced UE receiver technique, the problem of time difference of multipath transmission could be resolved, so that the interference from neighbor cells could be eliminated; the diversity effect of multiple cells co-frequency transmission could resolve problem of blind area, improve the reliability of receiving, and MBMS coverage rate.
The characteristic of MBMS multiple cells transmission technology comprises: synchronization transmission of MBMS in MBSFN area; supporting combination of MBMS multiple cells transmission; MBMS point-to-multipoint traffic channel (MTCH) and MBMS point-to-multipoint control channel (MCCH) is mapped on multicast channel (MCH) used for point to multi-point (PTM) transmission; MBSFN synchronization area could be semi-statically configured by operation and maintenance (O&M) system etc.
The spectral efficiency of MBMS could be 2 bps/Hz or higher, if the bandwidth of carrier wave is 20 MHz, then each sub-frame could at least carry 40 k bit information. For improving utilization rate of frequency resource, it could use statistical multiplexing in multiple streams transmission system, obtaining multiplexing gain by multiplexing multiple streams on shared resource. To MBMS multiple cells transmission, multiple MBMS could, multiple MBMS could be mapped on same MCH, it could obtain dynamic multiplexing gain by allocating resource to MCH correctly and dynamically scheduling to multiple MBMS on MCH.
Content synchronization mechanism of multiple cells transmission should meet the following condition: all base stations in MBSFN synchronization area acquire synchronization wireless frame timing, so that wireless frames could be sent at one time; all base station perform same radio link control (RLC)/media access control (MAC)/physical (PHY) layer configuration to same MBMS or same MCCH control message; evolution multimedia broadcast multicast service (EMBMS) gate way (GW) broadcasts MBMS packet with SYNC protocol to each base station for sending service in grouping; all base stations send MCCH message by specified resource on air interface at specified transmission time, and send MBMS data under SYNC protocol.
In addition, it defines MBMS point-to-multipoint scheduling channel (MSCH) in LTE system, to ensure base stations send data of multiple MBMS in synchronization in a certain scheduled interval.
In process to achieve the present invention, the inventor find that there are at least the following problems in the existing technology:
By the design of the existing system, after base station has received synchronization data frames of all services, there is no mechanism to perform dynamic scheduling to different services, so the existing technology couldn't ensure the synchronization scheduling of service data in all base stations in MBSFN area, it is difficult to perform synchronization multiplexing transmission of multiple MBMS, accordingly, MSCH couldn't be scheduled in synchronization.